Drum-type washing machine having damper and method

ABSTRACT

A drum-type washing machine having a damper, and method, capable of effectively reducing vibration of a water tub includes a housing, a water tub in the housing, and a damper unit having one end affixed to an outer surface of the water tub and an other end affixed to the housing. The damper unit includes a cylinder having one end affixed to one of the housing and the water tub and a piston having one end affixed to the other one of the housing and the water tub and the other end in the cylinder elastically retractable to reduce the transmitted vibration. A frictional pad is on an inner surface of the cylinder or an outer surface of the piston to come into frictional contact, respectively, with the outer surface of the piston or the inner surface of the cylinder, thereby reducing the vibration of the water tub.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit from Korean Patent Application No. 2004-91469, filed on Nov. 10, 2004 in the Korean Intellectual Property Office, the disclosure of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a drum-type washing machine, and, more particularly, to a drum-type washing machine including a damper to reduce vibration transmitted to a water tub, and method.

2. Description of the Related Art

In general, a drum-type washing machine is an apparatus in which laundry contained in a cylindrical rotating tub is raised and subsequently falls down during rotation of the rotating tub, so as to be washed by virtue of an impact applied thereto when the laundry falls down.

A conventional drum-type washing machine, as disclosed in Japanese Patent Laid-Open No. 2000-237490, includes an external housing, a cylindrical water tub installed in the housing and configured to contain wash water supplied from an opened side, and a cylindrical rotating tub installed in the water tub. The rotating tub is configured to rotate by a driving force from a drive motor mounted in a lower region of the housing. The rotating tub has a plurality of through-holes perforated at a circumferential wall thereof for the in-flow or out-flow of wash water.

The water tub is provided, at an upper side thereof, with suspension springs that elastically support the water tub in a suspended state inside the housing. The water tub is provided, at a lower side thereof, with damper units that support the water tub in a shock absorbing manner to reduce vibration generated during the operation of the washing machine.

Each damper unit includes a circular hollow cylinder, a piston having one end reciprocably received inside the cylinder, and one or more frictional pads disposed around an outer surface of the piston to come into frictional contact with an inner surface of the cylinder and configured to emit a force applied to the piston due to vibration transmitted from the water tub, in the form of heat, thereby enabling reduction of the vibration.

In the conventional drum-type washing machine configured as stated above, however, even if a low degree of vibration is generated in the water tub, as the rotating tub rotates at a high speed, the vibration is entirely transmitted to the housing since the frictional force acts between the frictional pad and the inner surface of the cylinder.

SUMMARY OF THE INVENTION

Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the invention.

The present invention addresses the above mentioned problem, and an aspect of the invention provides a drum-type washing machine which can effectively reduce various degrees of vibration transmitted to a water tub.

In accordance with one aspect of the present invention a drum-type washing machine includes an external housing, a water tub mounted in the housing in a suspended state, and a damper unit having one end affixed to an outer surface of the water tub and the other end affixed to the housing to thereby reduce vibration of the water tub. The damper unit includes a cylinder having one end affixed to one of the housing and the water tub and an other end having an opening. The damper unit also includes a piston having one end affixed to the other one of the housing and the water tub and the other end reciprocably received in the cylinder. The piston is retractable and reduces the vibration. The damper unit also includes a frictional pad positioned on an inner surface of the cylinder or an outer surface of the piston to come into frictional contact with, respectively, the outer surface of the piston or the inner surface of the cylinder, thereby reducing the vibration transmitted from the water tub to the piston.

According to an aspect of the present invention, the piston includes a first rod having one end affixed to one of the housing and the water tub and an other end inserted in the cylinder, and a second rod in the cylinder and connected to the first rod by an elastic member.

According to another aspect of the present invention, the second rod has a plurality of grooves recessed in an outer surface thereof for the insertion of the respective frictional pads.

According to another aspect of the present invention, a plurality of frictional pads are provided including a first frictional pad interposed between the inner surface of the cylinder and an outer surface of the first rod, and a second frictional pad interposed between the inner surface of the cylinder and an outer surface of the second rod.

According to another aspect of the present invention, the first rod has a first groove recessed in the outer surface thereof for the insertion of the first frictional pad, and the second rod has a second groove recessed in the outer surface thereof for the insertion of the second frictional pad.

According to another aspect of the present invention, the cylinder has a first groove recessed in the inner surface thereof for the insertion of the first frictional pad, and the second rod a second groove recessed in the outer surface thereof for the insertion of the second frictional pad.

In accordance with another aspect of the present invention, a drum-type washing machine includes an external housing, a water tub mounted in the housing in a suspended state, and a damper unit having one end affixed to an outer surface of the water tub and the other end affixed to the housing to thereby reduce vibration of the water tub. The damper unit includes a cylinder having one end affixed to one of the housing and the water tub and the other end having an opening. The damper also includes a first rod having one end affixed to the other one of the housing and the water tub and the other end reciprocably received in the cylinder and a second rod in the cylinder and connected to the first rod by an elastic member. The damper also includes a frictional pad interposed between an inner surface of the cylinder and an outer surface of at least one of the first and second rods and coming into frictional contact with the inner surface of the cylinder, thereby reducing the vibration transmitted from the water tub to the piston.

According to an aspect of the present invention, a method of reducing vibration in a washing machine is provided. In another aspect of the present invention, a damper reducing vibration is provided.

Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will become apparent and more easily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a perspective view of a drum-type washing machine in accordance with the present invention;

FIG. 2 is a sectional view of a damper unit included in the drum-type washing machine in accordance with a first embodiment of the present invention;

FIG. 3 is a sectional view of a damper unit included in the drum-type washing machine in accordance with a second embodiment of the present invention; and

FIG. 4 is a sectional view of a damper unit included in the drum-type washing machine in accordance with a third exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below to explain the present invention by referring to the figures.

FIG. 1 illustrates a drum-type washing machine according to an embodiment of the present invention. The drum-type washing machine includes an external housing 10, a cylindrical water tub 11 installed in the housing 10 and configured to contain wash water, and a cylindrical rotating tub 12 installed in the water tub 11.

The water tub 11 and the rotating tub 12 each have an opening at their front sides to put laundry into, or take it laundry out of, the rotating tub 12. A door 13 is hinged at a front side of the housing 10 to open or close the openings of the water tub 11 and the rotating tub 12.

The water tub 11 is suspended in the housing 10 by means of at least one suspension spring 14 coupled to an upper side of the water tub 11 to elastically support the water tub 11. A drainage pipe 15 and a drainage pump 16 are mounted at a lower side of the water tub 11 to discharge wash water to the outside.

The rotating tub 12 is configured to rotate upon receiving a driving force from a drive motor 17 mounted in a lower region of the housing 10. The rotating tub 12 has a plurality of through-holes 12 a at a circumferential wall thereof for the inflow or outflow of wash water. A plurality of lifters 12 b protrude inwardly from an inner surface of the rotating tub 12 to raise laundry contained in the rotating tub 12 and to thereby wash the laundry by virtue of an impact applied to the laundry when the laundry falls down.

The drum-type washing machine further includes a damper unit 20 that supports the water tub 11 in a shock absorbing manner to reduce vibration generated in the water tub 11 as the rotating tub 12 rotates.

FIG. 2 illustrates a first embodiment of the damper unit. As shown in FIG. 2, the damper unit 20 includes a hollow cylinder 21 having one end affixable to a bottom surface of the housing 10. The damper unit 20 also includes a piston 22 having one end affixed to a lower portion of an outer surface of the water tub 11 and the other end reciprocably received in the cylinder 21. The damper unit 20 also includes a frictional pad 23 positioned around the piston 22 to come into frictional contact with an inner surface of the cylinder 21 as the piston 22 reciprocates in the cylinder 21. Thereby, the frictional pads 23 act to convert a force applied to the piston 22 due to vibration transmitted from the water tub 11 into heat, and thus reducing the effective vibration.

In the first example embodiment of the present invention, the piston 22 is variable in length in an elastic manner. When a low degree of vibration is transmitted from the water tub 11 to the piston 22, the vibration is sufficiently reduced as the piston 22 is elastically contracted. Therefore, an action of a frictional force between the frictional pad 23 and the inner surface of the cylinder 21 is not required. Thus, transmission of the vibration to the outside is reduced.

To achieve such an elastically retractable configuration, the piston 22 includes a first rod 22 a having one end hingedly attached to the water tub 11 and an other end inserted in the cylinder 21. A second rod 22 b is installed in the cylinder 21 so as to reciprocate upon receiving a force from the first rod 22 a. An elastic member 22 c is positioned between the first rod 22 a and the second rod 22 b so as to connect the first and second rods. The elastic member 22 c is made of an elastically deformable material and configured to absorb part of the force transmitted from the first rod 22 a and transmit the remaining force to the second rod 22 b, thereby causing the second rod 22 b to reciprocate inside the cylinder 21.

According to another example embodiment of the present invention, a pair of the frictional pads 23 are axially arranged in parallel around the second rod 22 b. The second rod 22 b has a pair of grooves 22 d for the insertion of the frictional pads 23.

With the damper unit 20 of the first example embodiment, when a force that is less than an absorbing power of the elastic member 22 c is applied to the piston 22 due to a vibration of the water tub 11, the elastic member 22 c completely absorb the force as the elastic member 22 c is elastically deformed, i.e. contracted and expanded, thereby reducing the vibration of the water tub 11. On the other hand, when a force greater than the absorbing power of the elastic member 22 c is applied to the piston 22 due to the vibration of the water tub 11, only part of the force is absorbed as the elastic member 22 c is elastically deformed, i.e., contracted and expanded. The remaining force is absorbed as the frictional pad 23 affixed around the second rod 22 b moves within the cylinder 21 and is in frictional contact with the inner surface of the cylinder 21.

FIG. 3 illustrates a second example embodiment of the damper unit for use in the drum-type washing machine in accordance with the present invention.

The damper unit of the second embodiment, designated as reference numeral 30, includes a hollow cylinder 31, e.g., circular in shape having one end affixed to the bottom surface of the housing 10, a piston 32 having one end affixed to a lower location of the outer surface of the water tub 11 and the other end reciprocably received in the cylinder 31. The damper unit also includes frictional pads 33 and 34 arranged around the piston 32 so as to come into frictional contact with an inner surface of the cylinder 31 as the piston 32 reciprocates in the cylinder 31 to convert a force applied to the piston 32 due to the vibration of the water tub 11 into heat, thereby enabling reduction of the vibration.

The piston 32 includes a first rod 32 a having one end hingedly attached to the water tub 11 and the other end within the cylinder 31. A second rod 32 b is positioned in the cylinder 31 so as to reciprocate upon receiving a force from the first rod 32 a. An elastic member 32 c is interposed between the first rod 32 a and the second rod 32 b so as to connect them to each other, the elastic member 32 c made of an elastically deformable material and configured to absorb part of the force transmitted from the first rod 32 a and transmit the remaining force to the second rod 32 b, thereby reciprocating the second rod 32 b inside the cylinder 31.

In the second example embodiment, the frictional pads 33 and 34 include a first frictional pad 33 positioned around the first rod 32 a and a second frictional pad 34 positioned around the second rod 32 b. The first and second rod 32 a and 32 b have first and second grooves 32 d and 32 e, respectively, for the insertion of the first and second frictional pads 33 and 34.

With the damper unit 30 of the second example embodiment, when a force less than a sum of a frictional force acting between the first and second frictional pads 33 and 34 and the inner surface of the cylinder 31 and an absorbing power of the elastic member 32 c is applied to the piston 32 part of the force is absorbed as the first frictional pad 33 affixed on the first rod 32 a moves along in the cylinder 31 coming in frictional contact with the inner surface of the cylinder 31. The remaining force is absorbed as the elastic member 22 c is elastically deformed, i.e. contracted and expanded.

On the other hand, when a force greater than the sum of a frictional force acting between the first and second frictional pads 33 and 34 and the inner surface of the cylinder 31 and an absorbing power of the elastic member 32 c is applied to the piston 32, part of the force is absorbed as the elastic member 32 c is elastically deformed, i.e. contracted and expanded, and the remaining force is absorbed as the frictional pads 33 and 34 move within the cylinder 31 coming into frictional contact with the inner surface of the cylinder 31.

FIG. 4 illustrates a third example embodiment of a damper unit 40 in accordance with the present invention. While the second example embodiment included a first groove 32 d for the insertion of the first frictional pad 33 recessed in an outer surface of the first rod 32 a of the piston 32, the third example embodiment includes a first groove 41 a for the insertion of a first frictional pad 43 recessed in an inner surface of the cylinder 41. In this case, an inner surface of the first frictional pad 43 comes into frictional contact with an outer surface of a first rod 42 a of a piston 42, enabling reduction of the vibration. The third embodiment can also include a second rod 42 b having a groove 42 d for a second frictional pad 44.

According to aspects of the present a damper unit, for use in a drum-type washing machine, in which a piston is elastically retractable to reduce vibration applied thereto is provided. With such a damper unit, if a relatively low degree of vibration is applied to the piston, the vibration can be reduced simply as the piston is elastically contracted and expanded without assistance of frictional pads configured to come into frictional contact with the inner surface of a cylinder or the outer surface of the piston. Such a configuration enables a more effective reduction of the vibration transmitted from a water tub to the piston.

Although the embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents. 

1. A drum-type washing machine comprising: a housing; a water tub suspendedly mounted in the housing; and a damper unit having one end affixed to an outer surface of the water tub and an other end affixed to the housing reducing vibration of the water tub, the damper unit comprising: a cylinder having one end affixed to one of the housing and the water tub and an other end having an opening, a piston having one end affixed to the other one of the housing and the water tub and an other end reciprocably received in the cylinder and retractable, and a frictional pad on an inner surface of the cylinder or an outer surface of the piston coming in frictional contact, respectively, with the outer surface of the piston or the inner surface of the cylinder reducing vibration transmitted from the water tub to the piston.
 2. The washing machine according to claim 1, wherein the piston comprises: a first rod having one end affixed to one of the housing and the water tub and an other end within the cylinder, and a second rod in the cylinder and connected to the first rod by an elastic member.
 3. The washing machine according to claim 2, wherein the second rod has a groove recessed in an outer surface thereof for the positioning of the frictional pad.
 4. The washing machine according to claim 2, wherein the frictional pad is a plurality of frictional pads and comprises: a first frictional pad interposed between the inner surface of the cylinder and an outer surface of the first rod, and a second frictional pad interposed between the inner surface of the cylinder and an outer surface of the second rod.
 5. The washing machine according to claim 4, wherein the first rod has a first groove recessed in the outer surface thereof for the positioning of the first frictional pad, and the second rod has a second groove recessed in the outer surface thereof for the positioning of the second frictional pad.
 6. The washing machine according to claim 4, wherein the cylinder has a first groove recessed in the inner surface thereof for the positioning of the first frictional pad, and the second rod has a second groove recessed in the outer surface thereof for the positioning of the second frictional pad.
 7. A drum-type washing machine comprising: a housing; a water tub mounted in the housing; and a damper unit having one end affixed to an outer surface of the water tub and the other end affixed to the housing reducing vibration of the water tub, the damper unit comprising: a cylinder having one end affixed to one of the housing and the water tub and the other end having an opening, a first rod having one end affixed to the other one of the housing and the water tub and the other end reciprocably received in the cylinder; a second rod received in the cylinder and connected to the first rod by an elastic member; and a plurality of frictional pads between an inner surface of the cylinder and an outer surface of at least one of the first and second rods and configured to come in frictional contact with an inner surface of the cylinder reducing the vibration transmitted from the water tub to the piston.
 8. A washing machine comprising: a housing; a water tub mounted in the housing; and a damper having one end affixed to an outer surface of the water tub and an other end affixed to the housing, the damper unit comprising: a cylinder having one end affixed to one of the housing and the water tub, a piston having one end affixed to the other one of the housing and the water tub and an other end within the cylinder, the piston comprising: a first rod having one end affixed to one of the housing and the water tub and the other end within the cylinder, and a second rod in the cylinder and connected to the first rod by an elastic member, and a frictional pad on an inner surface of the cylinder or an outer surface of the piston positioned to come in frictional contact with the outer surface of the piston or the inner surface of the cylinder, respectively,
 9. The washing machine according to claim 8, wherein the second rod has a groove.
 10. The washing machine according to claim 8, wherein the frictional pad is a plurality of frictional pads and comprises: a first frictional pad positioned between the inner surface of the cylinder and an outer surface of the first rod, and a second frictional pad between the inner surface of the cylinder and an outer surface of the second rod.
 11. The washing machine according to claim 10, wherein the first rod has a first groove in the outer surface, and the second rod has a second groove in the outer surface thereof.
 12. The washing machine according to claim 10, wherein the cylinder has a first groove in the inner surface thereof, and the second rod has a second groove in the outer surface thereof.
 13. A method of reducing vibration in a washing machine, the method comprising: absorbing a first value of vibration by elastic deformation of an elastic member; and absorbing a second value of vibration by the elastic deformation of the elastic member and by friction between surfaces.
 14. The method of reducing vibration in a washing machine according to claim 14, wherein the second value of vibration is greater than the first value of vibration.
 15. A damper comprising: a cylinder having one end affixable to one of a housing and a movable part within the housing; a piston having one end affixed to the other one of the housing and the movable part and an other end within the cylinder; the piston comprising a first rod having one end affixed to one of the housing and the movable part and the other end within the cylinder, and a second rod in the cylinder and connected to the first rod by an elastic member; and a frictional pad positioned on an inner surface of the cylinder or an outer surface of the piston positioned to come in frictional contact with the outer surface of the piston or the inner surface of the cylinder, respectively.
 16. The damper according to claim 15, wherein the second rod has a groove.
 17. The damper according to claim 15, wherein the frictional pad is a plurality of frictional pads and comprises: a first frictional pad positioned between the inner surface of the cylinder and an outer surface of the first rod, and a second frictional pad between the inner surface of the cylinder and an outer surface of the second rod.
 18. The damper according to claim 15, wherein the first rod has a first groove in the outer surface thereof, and the second rod has a second groove in the outer surface thereof.
 19. The damper according to claim 15, wherein the cylinder has a first groove in the inner surface thereof, and the second rod has a second groove in the outer surface. 